1. Field of the Invention
This invention relates to hydroprocessing of petroleum oils, particularly those containing residual hydrocarbon components and having significant sulfur content. More particularly, the invention relates to a novel hydroprocessing catalyst, or catalyst system, for simultaneously reducing the sulfur content and the pour point of heavy petroleum oils containing residual hydrocarbon components. Said novel catalyst comprising hydrogenation components on a support containing a minor amount of a ZSM-5 type zeolite.
2. Description of the Prior Art
It has been conventional in the art to effect sulfur removal from hydrocarbon stocks by subjecting them to treatment with hydrogen, at elevated temperature and pressures, while in contact with a catalyst containing hydrogenating components, either supported or unsupported. Typical of the catalysts suggested by the prior art are those containing Group VIA or Group VIII metals, or their oxides or sulfides, as the hydrogenating components, with such hydrogenating components being supported on a variety of well-known carriers, such as, for example, alumina, kieselguhr, zeolitic molecular sieves and other materials having high surface areas.
Typical of the prior art are U.S. Pat. No. 3,546,103 which teaches hydrodesulfurization with a catalyst of cobalt and molybdenum on an alumina base; U.S. Pat. No. 3,755,145 which describes a process for preparing lube oils characterized by low pour points, it utilizes a catalyst mixture comprising hydrogenation components, a conventional cracking catalyst which can be either crystalline or amorphous and a crystalline aluminosilicate of the ZSM-5 type; and U.S. Pat. No. 3,894,938 relates to the catalytic dewaxing and desulfurization of high pour point, high sulfur gas oils to lower their sulfur content by contacting such oil first with a ZSM-5 type zeolite hydrodewaxing catalyst, which may contain a hydrogenation/dehydrogenation component, in the presence or absence of added hydrogen followed by conventional hydrodesulfurization processing of the dewaxed intermediate.
Although the art of hydroprocessing has been known for a long time and is a highly developed art, there exists today even greater need for efficient and economical means for hydrosulfurizing resids in order to make them more valuable refinery charge stocks. Heavy resids in particular contain large amounts of sulfur and other contaminants which result in undesirable effects such as corrosion, pollution or poisoning of the catalyst. Therefore, the removal or at the least a significant reduction in the amount of such contaminants is essential to the upgrading of such stocks. However, in order to provide a suitable upgrading stock other foreign elements such as metals, nitrogen, oxygen and halogen material also need to be removed from the residua. Typically the severe conditions of prior art hydrodesulfurization processes employ temperatures in the range of about 400.degree.-900.degree. F. or more, pressures of about 500 to 3000 psig and LHSV of about 0.2 to about 5 and are simply uneconomical and in their own right create additional problems. None of the prior art mentioned above nor any prior art known to applicant discloses a catalyst which is capable of simultaneously hydrodewaxing and hydrodesulfurizing heavy residual petroleum stocks.